The present invention relates to a developing-unit shifting apparatus used in an image forming apparatus, such as an electronic copying machine.
Recently copying machines have been developed which perform multicolor copying. One such copying machine comprises a plurality of developing units which are stored individually with developing agents of different colors. These developing units are supported so that they can be associated with and disengaged from a photoconductive drum. Only one of the developing units, which contains the developing agent of a designated color, is selected and brought into contact with the drum.
The surface of the photoconductive drum is very susceptible to damage. If the selected developing unit is always in contact with the drum as aforesaid, therefore, the drum may possibly be damaged. If copying is effected with use of such a damaged drum, the quality of resulting images will be poor.